Muffler



Nov. 7, 1933. G. M. HARTSOCK MUFFLER Filed Oct. 50

I N VEN TOR.

ATTO

Patented Nov. 7, 1933 PATENT OFFICE MUFFLER Guy M. Hartsock, South Bend, Ind., assignor, by mesne assignments, to C. F. Burgess Labora-- tories, Inc., Madison, Wis., a corporation of Delaware Application October so, 1930. Serial No. 492,162

'1 Claims. (01. 137-160) This invention relates to mufller construction and in its specific form to mufflers associated with the exhaust of internal combustion engines.

It is an object of the invention to mufiie the sound of rapidly moving fluids.

Another object relates to the absorption of sound created by the exhausting of gases from an internal combustion engine.

A further object pertains to the absorption of sound from the exhaust of an internal combustion engine without interfering to any substantial extent with the free passage of the exhaust gases.

Another object relates to the mufliing of the sound of exhaust gases from an internal combustion engine without the creation of back pressure, and without substantial power loss.

A further object comprises a novel mufller construction disposed on an exhaust pipe, and affording a free and unobstructed passage of gases through the exhaust pipe, the mufiiing taking place in a direction transverse to the direction of flow of the gases.

A more specific object resides in a mufller construction forming a portion of an exhaust pipe, and having a longitudinal passage permitting a clear passage of the exhaust gases, having its inner wall formed as a sound absorbing surface. In its specific embodiment the said inner wall will offer a great amount of sound absorbing surface relative to the cross-sectional area of the longitudinal passage.

Other objects will be disclosed in the detailed description of the invention.

Referring to the drawing which illustrates one form of mufiier incorporating features of the invention,

Fig. 1 is a side elevation of an automobile chassis showing the novel mufiler in position on the exhaust pipe;

Fig. 2 is a side view of the muffler, per se;

Fig. 3 is a cross sectional view of the novel muffler construction taken along the section line 33 of Fig. 2; and

Fig. 4 is a longitudinal view of the muflier taken along the section line 44 of Fig. 3.

The invention will be better understood from a description of the drawing which is to be taken as illustrative only, in which:

A muflier 10, of similar construction at both ends, is formed with an outer wall 11, preferably circular, and end walls 12 which are formed with reduced central tubular portions 13 adapted to be attached to sections of the exhaust pipe of an automobile and having a cross section throughout its length approximately equal to the cross section of the exhaust pipe. A centrally disposed pipe 14 adapted to form a longitudinal passage for the gases, is gradually reduced at its ends to form portions 15 adapted to be received within reduced portions 13 of the end walls. Pipe 14 is provided with numerous perforations 16 disposed over its surface for permitting passage of gases between pipe 14 and an annular space 1'7 formed between the outer wall 11 and the pipe 14. This annular space may be filled with steel wool or other sound absorbing material 18.

The cross section of pipe 14 is of an area not substantially less than and preferably about equal to that of the cross section of tubular portions 13, and is formed other than circular in shape in order that the pipe 14 provide a maximum amount of sound absorbing surface. The pipe 14 is preferably corrugated longitudinally and is illustrated as having a cross-section shaped similarily to a four-pointed star, but it is to be understood that the cross section may be of any form which has a ratio of periphery to area greater than a circular cross section.

In the construction described, the gases to be muffled pass through pipe 14 without impedance, and hence without power loss occasioned by back pressure. The sound waves are dissipated transversely of the direction of flow of the gases by virtue of perforations 16 leading into the annular space 17.

Various changes in the design and proportions of the preferred form shown in the drawing are contemplated as being within the spirit and concept of the invention.

What I claim as my invention is:

1. A mufller comprising a pipe having a portion of substantially star-shaped cross-section provided with openings therein forming a unidirectional gas passage through the muffler, said pipe being adapted to be connected at one end with 2. gas conduit and to form a continuation thereof, a tubular member surrounding said starshaped portion of said pipe and forming with said pipe a closed annular space, and sound absorbing material filling said annular space, the openings in said pipe being so positioned as to direct the sound impulses carried by the exhaust into the maximum thickness of said sound absorbing material.

2. An exhaust muffler comprising, a cylindrical shell, a tubular member at each end of said shell for connecting the shell to the exhaust inlet and outlet conduits, a duct within said shell having cylindrical end portions received in said tubular members and an intermediate portion having a star-shaped cross section, and sound absorbing material filling the space between said duct and said casing, said intermediate portion 01 said duct being provided with perforations so positioned as to direct the sound impulses carried by the exha into the maximum thickness of said sound absorbing material.

3. An exhaust mufiler comprising, a cylindrical shell, a flanged tubular member at each end of said shell for connecting said shell to the exhaust inlet and outlet conduits, a duct within said shell having cylindrical end portions received in said tubular members and an intermediate portion of substantially polygonal cross-section, the sides between the edges thereof being bent inwardly to increase the area of said duct per unit of length and to increase the thickness of the space between said duct and said casing, and sound absorbing material in the space between said duct and said casing, the intermediate portion of said duct being provided with perforations so posi tioned as to direct the sound impulses carried by the exhaust into the maximum thickness of said sound absorbing material.

4. A muiller for the noise-producing exhaust gas or an internal combustion engine comprising the combination of a duct with a lining of a sound absorbing material, said duct offering practically no resistance to the flow of said gas therethrough, the thickness of said lining varying substantially in any transverse plane along the greater part of its length, the maximum thickness of said lining in a given one of said transverse planes being at least twice the minimum thickness in the same transverse plane.

5. A muflier for the noise-producing exhaust gas 01' an internal combustion engine comprising in combination, a duct having a ioraminous wall, a contiguous backing for said duct comprising a sound absorbing material, and an outer casing surrounding said absorbing material, the outer casing being so spaced from said duct that the thickness of said absorber varies substantially in any transverse plane along the greater part of its length, the maximum thickness 01 said absorber in a given one of said transverse planes being at least twice the minimum thickness in the same transverse plane, said duct forming a substantially straight passage for the gas and offering practically no resistance to its flow therethrough.

6. A muiiler for noise-producing gas comprising a substantially straight duct, a lining 01 sound absorbing material for said duct, said duct forming a substantially straight passage for the gas and offering practically no resistance to its flow therethrough, the thickness of said lining varying substantially. in any transverse plane along the greater part of its length, the maximum thickness of said absorbing material in some transverse planes being at least twice the minimum thickness in the same transverse planes.

7. A mufiler comprising the combination of a sound absorbing material with a duct therethrough, the thickness of said absorbing material varying substantially in any transverse plane along the greater part of its length, the maximum thickness of said absorbing material in a given one or said transverse planes being at least twice the minimum thickness in the same transverse plane.

GUY M. HAR'ISOCK. 

